The present invention relates to an apparatus for the regeneration of the active carbon used in waste water treatment and so forth.
Some of the present inventors have previously proposed a regeneration apparatus for spent carbon, which facilitates the mixing of spent active carbon and provides a satisfactory regeneration effect (cf. Japanese Patent Application No. 7484/1973 corresponding to U.S. Pat. No. 4,007,014; U.S. Ser. No. 575,597, now U.S. Pat. No. 4,008,994). This previously proposed apparatus is devised such that in the center of a vertical heating furnace provided with at least one burner, a regeneration gas supply system and a duct with a damper, there is inserted an outer cylinder having a feed inlet for the spent active carbon disposed at the upper end thereof and a device for discharging the resulting product disposed at the lower end thereof. An inner cylinder sealed at the lower end thereof and having a regeneration gas supply system and a duct with a damper is inserted in said outer cylinder concentrically therewith. A multiplicity of inclined annular plates with a slope steeper than the angle of repose of the spent active carbon are provided in vertically multi-stage fashion on both the inner periphery of said outer cylinder and the outer periphery of said inner cylinder by vertically staggering the inclined annular plates of the outer cylinder relative to the inclined annular plates of the inner cylinder. A plurality of penetrating holes are bored in both the wall of said outer cylinder and the wall of said inner cylinder.
In a regeneration apparatus devised as above, the spent active carbon is fed through the top of the annular regeneration chamber composed of the outer cylinder and the inner cylinder, and is subjected to indirect heating with the flue gas from the heating furnace mainly through the outer cylinder wall. Meanwhile, the regeneration gas such as steam, etc. flows in the annular regeneration chamber mainly through the holes penetrating the inner cylinder wall, and the spent active carbon comes in contact with the regeneration gas in this chamber and is subjected to the drying, calcination and reactivation processes, in that order, as it descends from the top to the bottom inside the regeneration chamber, thereby to be generated as product.
This double-cylinder type regeneration apparatus designed to heat through the outer cylinder is suitable for a small-size apparatus, but it is not always suitable for a large-scale operation employing a large-size apparatus. That is, according to this type of apparatus, there is a limit to the enlargement of the clearance of said annular regeneration chamber (to wit, the interspace between the outer and the inner cylinders) for the purpose of securing the necessary heat transfer to the spent active carbon within the annular regeneration chamber. Besides, inasmuch as the central passage within the inner cylinder does not take part in the heat transfer, in order to enhance the regeneration efficiency of the apparatus, the diameter of the inner and the outer cylinders must be enlarged while the clearance of the annular regeneration chamber is kept within limits, and accordingly, it is necessary to enlarge the diameter of the heating furnace. Consequently, the cost of construction of the apparatus and the operation expenses per unit amount of disposal of spent active carbon are affected thereby, and therefore this apparatus is rather disadvantageous from an industrial point of view.